Although it is still a “work” in progress, has a ton of bugs and is barely usable, it does provide a very nice feature: apparently, it will work under any platform where Mono is supported…
The emulator is being primarily designed to run under Windows, but with a few tweaks it will run under any platform that supports the Mono framework, such as any Linux distribution, Mac OS X (including Mavericks) and, quite surprisingly, it will even run on the Raspberry Pi!
So, here’s a link to download the x8086NetEmu’s binaries that have already been pre-compiled to run under the aforementioned platforms.
The binaries include both a WinForms version as well as a console (no GUI) version.
WARNING: This is a very CPU intensive program for the poor Raspberry Pi, so use it with care… you don’t want to fry your RPi!
NOTE: To run the emulator on the Raspberry Pi in console mode, you’ll just need to connect via SSH, as you normally do, but in order to test the WinForms version, you will need an X server.
If you are using a Mac, then you already have one, X11, but it you are running Windows I recommend Xming.
UPDATE (7/20/2016): The source code is now available at GitHub.